1. Field of the Invention
The present invention relates to a magnetoresistive element and a magnetic memory and, for example, to a magnetoresistive element and a magnetic memory which can record information by, e.g., supplying a current.
2. Description of the Related Art
MRAMs (Magnetic Random Access Memories; also referred to as magnetic memories hereinafter) using ferromagnetic materials are expected as nonvolatile memories ensuring nonvolatility, high-speed operation, large capacity, and low power consumption. An MRAM has, as a storage element, an MTJ (Magnetic Tunnel Junction) element using a TMR (Tunneling MagnetoResistive) effect, and stores information in accordance with the magnetization state of the MTJ element.
In a conventional MRAM that writes data on the basis of a magnetic field induced by a current, the value of the current flowing to the interconnection decreases along with microfabrication. It is therefore difficult to supply a sufficient magnetic field induced by a current. In addition, the magnitude of the magnetic field necessary for recording information in the MTJ element increases along with microfabrication. Hence, MRAMs of the 126- to 256-Mbit generation using the magnetic write scheme based on an interconnection current will soon reach their theoretical limits.
There is proposed an MRAM using a write scheme based on SMT (Spin Momentum Transfer) (e.g., U.S. Pat. No. 6,256,223). The SMT (to be referred to as spin injection hereinafter) rarely increases the current density necessary for magnetization switching even when the element becomes small. Hence, an efficient write is possible.